The ipv6 redirect target was derived from the ipv4 one, i.e. its identical to a 'dnat' with the first (primary) address assigned to the network interface. The code has been moved around to make it usable from nf_tables too, but its still the same as it was back when this was added in 2012. IPv6, however, has different types of addresses, if the 'wrong' address comes first the redirection does not work. In Daniels case, the addresses are: inet6 ::ffff:192 ... inet6 2a01: ... ... so the function attempts to redirect to the mapped address. Add more checks before the address is deemed correct: 1. If the packets' daddr is scoped, search for a scoped address too 2. skip tentative addresses 3. skip mapped addresses Use the first address that appears to match our needs. Reported-by: Daniel Huhardeaux <tech@xxxxxxxxxx> Closes: https://lore.kernel.org/netfilter/71be06b8-6aa0-4cf9-9e0b-e2839b01b22f@xxxxxxxxxx/ Fixes: 115e23ac78f8 ("netfilter: ip6tables: add REDIRECT target") Signed-off-by: Florian Westphal <fw@xxxxxxxxx> --- This bug is very old, we could also route this fix via nf-next if you think its too intrusive. net/netfilter/nf_nat_redirect.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nf_nat_redirect.c b/net/netfilter/nf_nat_redirect.c index 6616ba5d0b04..5b37487d9d11 100644 --- a/net/netfilter/nf_nat_redirect.c +++ b/net/netfilter/nf_nat_redirect.c @@ -80,6 +80,26 @@ EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4); static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT; +static bool nf_nat_redirect_ipv6_usable(const struct inet6_ifaddr *ifa, unsigned int scope) +{ + unsigned int ifa_addr_type = ipv6_addr_type(&ifa->addr); + + if (ifa_addr_type & IPV6_ADDR_MAPPED) + return false; + + if ((ifa->flags & IFA_F_TENTATIVE) && (!(ifa->flags & IFA_F_OPTIMISTIC))) + return false; + + if (scope) { + unsigned int ifa_scope = ifa_addr_type & IPV6_ADDR_SCOPE_MASK; + + if (!(scope & ifa_scope)) + return false; + } + + return true; +} + unsigned int nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range, unsigned int hooknum) @@ -89,14 +109,19 @@ nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range, if (hooknum == NF_INET_LOCAL_OUT) { newdst.in6 = loopback_addr; } else { + unsigned int scope = ipv6_addr_scope(&ipv6_hdr(skb)->daddr); struct inet6_dev *idev; - struct inet6_ifaddr *ifa; bool addr = false; idev = __in6_dev_get(skb->dev); if (idev != NULL) { + const struct inet6_ifaddr *ifa; + read_lock_bh(&idev->lock); list_for_each_entry(ifa, &idev->addr_list, if_list) { + if (!nf_nat_redirect_ipv6_usable(ifa, scope)) + continue; + newdst.in6 = ifa->addr; addr = true; break; -- 2.41.0
